Tractors and utility vehicles used for agriculture, lawn care or recreational use may have a hydrostatic transmission that drives a final drive transmission or range transmission of the vehicle. The final drive transmission or range transmission may drive at least one wheel. The vehicle speed may be operator modulated by changing the drive ratio of the hydrostatic transmission, as well as the range gears. The drive ratio may be changed by moving the angle of a swashplate of a variable displacement pump of the hydrostatic transmission.
Hydrostatic transmissions in tractors and utility vehicle may be operated using twin foot pedals to control the direction and speed of the vehicle, and a hand throttle or hand accelerator lever to control the engine speed. This allows operating the tractor at a fixed engine speed required for implements or attachments, while using a first foot pedal to pivot a swash plate in the hydraulic pump to an angular alignment in which hydraulic fluid provided to the hydraulic motors propels the vehicle forward at a desired ground speed, and a second foot pedal to pivot the swash plate to move the vehicle in reverse at a desired ground speed. If neither foot pedal is applied, the swash plate may be in a neutral position.
However, some tractor applications require frequent or continuous use of the hand throttle or hand accelerator lever to change engine speed between low and high engine RPM. For example, tractor applications such as operating a front end loader, driving the tractor at high speeds during road transport, or snow removal may require frequent or continuous changes to engine speed. An automatic throttle for a tractor with a twin pedal hydrostatic transmission offered by Deere & Company includes an electronic controller that provides engine speed commands based on the position of either of the twin throttle pedals. An automatic throttle for a tractor with a twin pedal hydrostatic transmission is needed that is lower in cost than an electronic controller. An automatic throttle for a tractor with a twin pedal hydrostatic transmission is needed that is low cost. An automatic throttle for a tractor with a twin pedal hydrostatic transmission is needed that eliminates frequent or continuous use of a hand throttle or hand accelerator lever to change engine speed.